This invention relates in general to an improved computer hard disk drive and in particular to avoiding catastrophic failure in a disk drive as long as possible. Still more particularly, the invention relates to a system and method for gracefully relinquishing a disk drive that is on the brink of catastrophic failure in order to transfer data from the failing drive to another storage medium.
Generally, a digital data access and storage system consists of one or more storage devices that store data on storage media such as magnetic or optical data storage disks. In magnetic disk storage systems, a storage device is called a hard disk drive (HDD), which includes one or more hard disks and an HDD controller to manage local operations concerning the disks. Hard disks are rigid platters, typically made of aluminum alloy or a mixture of glass and ceramic, covered with a magnetic coating. Typically, two or three platters are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
The only other moving part within a typical HDD is the head assembly. Within most drives, one read/write head is associated with each side of each platter and flies just above or below the platter""s surface. Each read/write head is connected to a semi-rigid arm apparatus which supports the entire head flying unit. More than one of such arms may be utilized together to form a single armature unit.
Each read/write head scans the hard disk platter surface during a xe2x80x9creadxe2x80x9d or xe2x80x9cwritexe2x80x9d operation. The head/arm assembly is moved utilizing an actuator which is often a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which is also mounted the spindle supporting the disks. The base casting is in turn mounted to a frame via a compliant suspension. When current is fed to the motor, the VCM develops force or torque which is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head nears the desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop directly over the desired track.
In rare circumstances, a disk drive will have a catastrophic failure wherein the data saved on the disk will be permanently lost and incapable of being retrieved. Unfortunately, prior art disk drives are incapable of delaying the onset of catastrophic failure in order to simultaneously transfer data from the failing drive to another known good drive or other storage medium.
Accordingly, it is an object of the invention to provide an improved computer hard disk drive.
It is an additional object of the invention to avoid catastrophic failure in a disk drive as long as possible.
Still another object of the invention is to provide a system and method for gracefully relinquishing a disk drive that is on the brink of catastrophic failure in order to transfer data from the failing drive to another storage medium.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.
A computer hard disk drive has a drive controller that monitors the condition of the head-disk interface within the drive. The drive normally operates under ambient or relatively low internal pressure. However, when the drive is in imminent risk for a head-disk interface failure, the drive is pressurized to allow the air bearing surfaces of the heads to achieve a greater flying height above the surfaces of their respective disks, thereby delaying the onset of a catastrophic head-disk interface failure. In addition, the spindle rotation rate and/or the slider head access rate are decreased to avoid hastening the imminent failure. Measurements of the condition and stability of the head-disk interface inside the drives are made by monitoring data error rates, head flying height, and other performance variables.